This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Determine the effect of Dimebon as compared to placebo on cognition as measured by the Mini-Mental State Examination (MMSE);and determine the effect of Dimebon as compared to placebo on the primary measure of global function, the Clinician's Interview-Based Impression of Change, plus caregiver input (CIBIC-plus).